This invention generally relates to a mechanical arrangement and more particularly, to a mechanical arrangement including an operational device for indicating and changing a state of the controlled device adjustable by an operator, e.g., amount of exposure of an electrophotographic copying apparatus.
Generally, in conventional mechanical arrangements, it has been so arranged that a subject or factor controllable by an operator such as exposure amount in an electrophotographic copying machine or the like is adjusted for example by changing a width of a slit with the use of an adjusting lever or by turning or sliding a variable resistor to a suitable extent.
The known arrangements as described above, however, have such disadvantage that, once the lever has been moved from a preset value (e.g., a standard value) for a normal operation to a certain value corresponding to a specific original to be copied, the operator may frequently fail to return the lever to the preset value before reverting to the normal operation, and thus, the copying apparatus is operated with the lever set to the value at the time of the previous operation.
For example, in conventional electrophotographic copying apparatuses, it has been generally arranged that an exposure amount adjusting device is of a lever type and, as is clear from the foregoing description, copying is undesirably performed with the amount of exposure being set to a value selected at the time of the previous copying, which results in improper copying.
Furthermore, in the conventional copying apparatuses, there has been such an inconvenience that, when the amount of exposure is changed from a preset value to a certain value so as to effect interrupt copying during the normal copying mode in which the amount of exposure is set to the preset value and then, the interrupt copying mode is reverted to the normal copying mode, the copying is effected with the amount of exposure set to the value selected for the interrupt copying unless the lever is reset to the preset value manually, which also results in faulty copying.
Moreover, in the conventional electrophotographic copying apparatuses, it has frequently happened that copying is effected, with the amount of exposure for the existing copying left unadjusted, for example, when the power source for the copying apparatus is turned on, when a predetermined number of copy paper has been copied, or when manual paper feeding mode is reverted to automatic paper feeding mode after the latter has been changed over to the former, thus resulting in the similar drawbacks as described above.
As is seen from the foregoing description, known mechanical arrangements have had a number of disadvantages and have presented a problem that an operator's great skill and caution in operation are required to overcome these disadvantages.